Oftentimes we read plans by overzealous trippers to drive long hours to "get it all in" on their allotted vacation time. Every time a veteran road tripper will advise, "Don't do it."
What about those times in whichyou really do need to fit in a long day of driving? The Wall Street Journalhas a helpful article on taking naps.
As you will read, how long of a nap you should take depends on what you need to accomplish. A power nap to get you another hour safely down the road? 10 to 15 minutes. Another 4 hours of driving until you bunk down for the night? Better make it 90 minutes.